Miniscript Template: 2
  Title: 5 Key Time Layered Multisig
  Created: 2023-09-11

Name of Template

5 Key Degrading Multisig

Goal to be achieved by template

Expanding upon the concept of a 3 key timed multisig, a 5 key timed multisig allows for multiple timelocks to be introduced for additional flexibility.

A timelock can be employed to allow a native 3 of 5 multisig to become 2 of 5, and eventually 1 of 5 for disaster recovery. This can be employed by using a miniscript `tresh()` with seven conditions:

3 Conditions to be satisfied by:

1. Key 1
2. Key 2
3. Key 3
4. Key 4
5. Key 5
6. First timelock (either relative or absolute)
7. Second timelock (either relative or absolute)

Timelock Values Note

• The security of the descriptor template is not dependent on the value of a relative or absolute timelock, as it only impacts the duration of the timelock. For reference transactions on testnet, short duration timelocks have been used, but in practice timelock values will differ.
• Relative timelock descriptors offer a structure that can persist across time, requiring a self-send to extend the timelock security, and thus offering a better ability to have standard timelock durations within templates.
• It is harder to set established timelock values with absolute timelock descriptors as they need to be regularly updated.

Suggested Relative Block Height Timelocks:

• older(32800) - Halfway point of block height relative timelock (~278 days assuming constant hashrate)

• older(65535) - maximum duration of a block height relative timelock (~455 days assuming constant hashrate)

Suggested Relative Epoch Timmelocks:

• older(4224680) - Approximate Halfway point of epoch time relative timelock (~180 days, 6 months)

• older(4259839) - Maximum duration of an epoch time relative timelock (~388 days)

Below is a reference diagram on how the 5 Key Time Layered Multisig operates across time:

Example Miniscript Output Descriptor

1. 5 Key Time Lock Multisig - Relative Blockheight Timelock

   wsh(thresh(3,pk(XPUB1),s:pk(XPUB2),s:pk(XPUB3),s:pk(XPUB4),s:pk(XPUB5),snu:older(100),snu:older(200)))

Reference Testnet Transaction

2. 5 Key Time Lock Multisig - Absolute Blockheight Timelock

   wsh(thresh(3,pk(XPUB1),s:pk(XPUB2),s:pk(XPUB3),s:pk(XPUB4),s:pk(XPUB5),snu:after(1694563200),snu:after(1694563200)))

Reference Testnet Transaction

3. 5 Key Time Lock Multisig - Absolute Epochtime Timelock

   wsh(thresh(3,pk(XPUB1),s:pk(XPUB2),s:pk(XPUB3),s:pk(XPUB4),s:pk(XPUB5),snu:after(1694563200),snu:after(1694476800)))

Reference Testnet Transaction

4. 5 Key Time Lock Multisig - Relative Epochtime Timelock

   wsh(thresh(3,pk(XPUB1),s:pk(XPUB2),s:pk(XPUB3),s:pk(XPUB4),s:pk(XPUB5),snu:older(4194400),snu:older(4194500)))

Reference Testnet Transaction

(To Add Taproot descriptors once Minitapscript is merged into Core)